Could I disclose sales numbers I helped a client get?

Question

Recently I've started sending some proposals to some possible clients. One of these new leads, is not a competitor but a company in the same city as one of my current clients, and in my proposal I was mentioning that I helped this client of mine achieve over X dollars in sales with my work (web design). My girlfriend read this and thinks it is not my place to disclose the amount of money I've help them generate — take into consideration that the site I made was from the beginning, so there were no previous numbers. Now I'm wondering, is it? I mean, I'm not telling an exact number, just something in the likes of "I help them make over $100k in sales with my services". Is this considered unprofessional? Or rude? Should I go ahead and ask this client if sharing am ambiguous number of sales is okay with them?

I'm a bit lost, any help or suggestions are appreciated

Answer 1

This seems to break down to three main elements; Legal, ethical and fiscal.

Legally:
You're free to do pretty much anything that you didn't contractually agree with your reference client that you would do. If that included non-disclosure of their sales figures to third parties, then you're not free to expose them. If you agreed to no such thing, then the only strictures would be the usual Data Protection laws in your locality.

Ethically:
Since they paid you a fee in good faith and haven't damaged the relationship from their own side, you do have a general moral responsibility to the wellbeing of your client (e.g. goodwill), and not to do things that would cause them harm or embarrassment. A pretty decent guide to whether your ethics are at fault would be that if your reference client accidentally found out what information you'd shared about them, that you think that it would make them unhappy.

Fiscally:
Depending on the business that you're in, your greatest chance of doing business is either with your existing client (with a very small chance of securing a new client) or vice versa. If there's very little need to protect an ongoing relationship with your old client, other than the need to use your work with them as a sales tool, then your obvious self-interest is to share as much information as possible, notwithstanding the legal and moral issues above.